An overheard and misunderstood conversation, a tweet and social-media messages prompted a police and school-district investigation of an unsubstantiated threat Tuesday night, officials said.

“It is an allegation. It is unsubstantiated,” Scott County Schools Superintendent Dr. Kevin Hub said Wednesday morning.

Hub made the comment as he stood alongside Principal Joe Pat Covington outside Scott County High School, where the two greeted parents and assured them their children faced no danger of rumored plan for a school shooting.

“I’ve had parent after parent after parent roll down their car window and say, ‘Thank you so much,’” Hub said.

Hub, his administrators and Georgetown police went into action Tuesday evening, after a parent sent a tweet directly to a friend, Assistant Police Chief Robert Swanigan said.

“It involved a very vague threat about not going to school Wednesday,” Swanigan said.

The tweet was reported to the police around 6:30 p.m., he said.

By that time, Swanigan said, the tweet had been “shared, shared and reshared” across social media.

Working with school administrators, police were able to determine the rumor originated from an overheard conversation in the SCHS cafeteria Tuesday, where some students were discussing an April 10 shooting at a San Bernardino, California, school.

In that shooting, a man killed his estranged wife — a teacher at the school — and an 8-year-old student before turning the gun on himself.

“Allegedly, it was a conversation that was overheard and misunderstood,” Hub said.

Concern over the rumor prompted school district officials to send out an alert Wednesday morning to reassure parents and students.

“Officers have assured us that the threat is not credible but, as an extra safety meaure, there will be added police presence on the campus of Scott County High School today,” the message stated.

Schools maintained their regular schedules.

Asked if the parent who sent the original tweet should have first contacted police, Swanigan said, “We would obviously have liked to have that information first. We would have loved to get that information much, much earlier.

“As with any threat like this, we take them very seriously and will give them the attention they deserve,” Swanigan said.